1. Field of the Invention
The present invention relates generally to magnetic sensors and particularly to magneto-resistive sensors.
2. Description of the Related Art
Magnetic storage media, such as magnetic storage tape systems and hard drives, rely on magnetic sensors to read data contained within the storage media. The magnetic sensor detects variations in a sensed magnetic field as the sensor passes over the media. The variations in the magnetic field may be used to read the data contained on the storage media.
One type of magnetic sensor used to read magnetic storage media is anisotropic magneto-resistive (AMR) sensors. Control of response characteristics for AMR sensors is an important design consideration for current and future magnetic tape heads. One method of controlling response characteristics involves the use of a periodic structure formed into the substrate on which the sensor stack is deposited. This periodic structure is commonly referred to as a grating.
The effect of the grating is to impart a short-range or localized magnetic field which acts on the magnetization of the sensor in such a way that the magnetization preferentially is directed parallel to the grating direction. This assists in the proper biasing of the AMR sensor magnetization which is close to 45 degrees. One problem with this design is that the edge definition and wall angles of the grating structure are lessened with each subsequent layer deposition in the magneto-resistive sensor. In addition, the grating is only created in the bottom regions of the AMR sensor structure, so avoiding this problem using current techniques is difficult, if not impossible. Therefore, it would be advantageous to have an improved method and apparatus for allowing an AMR sensor to have more layers deposited on the sensor, but without changing the topography in of the bottom region of the magneto-resistive sensor.